U.S. patent application number 11/963547 was filed with the patent office on 2008-10-23 for implant planning using captured joint motion information.
This patent application is currently assigned to MAKO Surgical Corp.. Invention is credited to Louis Arata, Alon Mozes, Jason Otto, Robert Van Vorhis.
Application Number | 20080262812 11/963547 |
Document ID | / |
Family ID | 39522691 |
Filed Date | 2008-10-23 |
United States Patent
Application |
20080262812 |
Kind Code |
A1 |
Arata; Louis ; et
al. |
October 23, 2008 |
Implant Planning Using Captured Joint Motion Information
Abstract
The description relates to surgical computer systems, including
computer program products, and methods for implant planning using
captured joint motion information. Data is captured representative
of a range of motion of a joint associated with a particular
individual, where the joint includes a first bone and a second
bone. The first bone of the joint is represented and a first
implant model is associated with the representation of the first
bone. Based on the captured data, a relationship is determined
between the first implant model and a representation of the second
bone through at least a portion of the range of motion of the
joint. Information is displayed representative of the determined
relationship.
Inventors: |
Arata; Louis; (Mentor,
OH) ; Mozes; Alon; (Miami Beach, FL) ; Otto;
Jason; (Plantation, FL) ; Van Vorhis; Robert;
(Davis, CA) |
Correspondence
Address: |
PROSKAUER ROSE LLP
ONE INTERNATIONAL PLACE
BOSTON
MA
02110
US
|
Assignee: |
MAKO Surgical Corp.
Fort Lauderdale
FL
|
Family ID: |
39522691 |
Appl. No.: |
11/963547 |
Filed: |
December 21, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60925269 |
Apr 19, 2007 |
|
|
|
Current U.S.
Class: |
703/11 |
Current CPC
Class: |
A61B 2034/102 20160201;
A61B 2034/105 20160201; A61B 2034/107 20160201; A61B 34/10
20160201; A61B 2034/252 20160201; A61F 2/389 20130101; A61B
2034/101 20160201; A61F 2/3859 20130101; G16H 50/50 20180101; G06F
19/00 20130101; A61B 34/20 20160201; A61B 2034/108 20160201; A61B
2034/2055 20160201; A61B 90/36 20160201; A61B 2034/104
20160201 |
Class at
Publication: |
703/11 |
International
Class: |
G06G 7/48 20060101
G06G007/48 |
Claims
1. A surgical planning method comprising: capturing data
representative of a range of motion of a joint associated with a
particular individual, the joint comprising a first bone and a
second bone; representing the first bone of the joint; associating
a first implant model with the representation of the first bone;
based on the captured data, determining a relationship between the
first implant model and a representation of the second bone through
at least a portion of the range of motion of the joint; and
displaying information representative of the determined
relationship.
2. The method of claim 1, further comprising enabling a user to
change a position of the first implant model.
3. The method of claim 2, further comprising: associating the first
implant model with the representation of the first bone based on
the changed position; and based on the captured data, determining a
relationship between the first implant model at its changed
position and a representation of the second bone through at least a
portion of the range of motion of the joint
4. The method of claim 1, wherein the representation of the second
bone includes a representation of a surface of the second bone, a
second implant model associated with the representation of the
second bone, or both.
5. The method of claim 1, wherein capturing comprises: tracking a
position of the first bone and a position of the second bone; and
recording the positions as the joint moves through the range of
motion.
6. The method of claim 1, further comprising: representing a
position of the first implant model relative to a position of the
representation of the second bone; and comparing the positions at
any selected angle within the range of motion of the joint,
inclusive.
7. The method of claim 1, further comprising: representing a
position of the first implant model relative to a position of a
second implant model associated with the second bone; and comparing
the positions at any selected angle within the range of motion of
the joint, inclusive.
8. The method of claim 1, wherein determining comprises identifying
an overlap, a gap, or both between the first implant model and the
representation of the second bone or between the first implant
model and a second implant model associated with the second bone at
one or more angles within the range of motion of the joint,
inclusive.
9. The method of claim 8, wherein displaying comprises displaying a
calculated measurement of the overlap, the gap, or both at any
selected angle or at a plurality of angles within the range of
motion of the joint, inclusive.
10. The method of claim 8, wherein displaying comprises displaying
of the overlap, the gap, or both in a representation of at least a
portion of the joint at one or more angles within the range of
motion of the joint, inclusive.
11. The method of claim 1, further comprising: mapping at least one
point on a surface of the first implant model at a plurality of
angles within the range of motion of the joint, inclusive; and
aligning at least one of the mapped points with the representation
of the second bone.
12. The method of claim 11, further comprising associating a second
implant model with the representation of the second bone based on
at least one of the mapped points.
13. The method of claim 1, wherein capturing further comprises
capturing data representative of a manipulation of the joint to
achieve a desired internal/external angle, varus/valgus angle,
flexion angle, or any combination thereof.
14. The method of claim 13, further comprising enabling a user to
manipulate placement of at least one implant model corresponding to
at least a portion of an actual implant so that the determined
relationship through at least a portion of the range of motion of
the joint allows the desired internal/external angle, varus/valgus
angle, flexion angle, or any combination thereof.
15. A computer program product, tangibly embodied in an information
carrier, the computer program product including instructions being
operable to cause a data processing apparatus to: capture data
representative of a range of motion of a joint associated with a
particular individual, the joint comprising a first bone and a
second bone; represent the first bone of the joint; associate a
first implant model with the representation of the first bone;
determine a relationship between the first implant model and a
representation of the second bone through at least a portion of the
range of motion of the joint based on the captured data; optionally
associate a second implant model with the representation of the
second bone; and display information representative of the
determined relationship.
16. A surgical planning method, comprising the steps of: capturing
data representative of a range of motion of a joint associated with
a particular individual, the joint comprising a first bone and a
second bone; creating a representation of the joint comprising a
representation of the first bone and a representation of the second
bone; superimposing a first implant model on the representation of
the first bone and a second implant model on the representation of
the second bone; based on the captured data, displaying the
representations of the first and second bones as the representation
of the joint moves through the range of motion to determine a
relationship between the first and second implant models; and
adjusting a size, a shape, a position, or any combination thereof
of the first implant model, the second implant model, or both based
on the determined relationship.
17. A computer program product, tangibly embodied in an information
carrier, the computer program product including instructions being
operable to cause a data processing apparatus to: capture data
representative of a range of motion of a joint associated with a
particular individual, the joint comprising a first bone and a
second bone; create a representation of the joint comprising a
representation of the first bone and a representation of the second
bone; superimpose a first implant model on the representation of
the first bone and a second implant model on the representation of
the second bone; display the representations of the first and
second bones as the representation of the joint moves through the
range of motion to determine a relationship between the first and
second implant models based on the captured data; and adjust a
size, a shape, a position, or any combination thereof of the first
implant model, the second implant model, or both based on the
determined relationship.
18. A surgical computing system comprising: a computer configured
to: capture data representative of a range of motion of a joint
associated with a particular individual; represent a first bone of
the joint; associate a first implant model with the representation
of the first bone; and based on the captured data, determine a
relationship between the first implant model and a representation
of a second bone of the joint through at least a portion of the
range of motion of the joint.
19. The surgical computing system of claim 18 further comprising a
tracking system in communication with the computer, the tracking
system including a detection device and one or more trackers which
each include a coupling means to couple the tracker to a bone of
the joint.
20. The surgical computing system of claim 18 further comprising a
display in communication with the computer and configured to
display information received from the computer that is
representative of the determined relationship.
21. The surgical computing system of claim 18 wherein the computer
is further configured to generate a user interface that enables a
user to select an angle at which the determined relationship is
calculated, displayed, or both.
22. The surgical computing system of claim 18 wherein the computer
is further configured to generate a user interface that enables a
user to change a position of the first implant model.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Provisional
Patent Application Ser. No. 60/925,269, filed on Apr. 19, 2007,
which is hereby incorporated by reference herein in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to surgical computer systems,
including computer program products, and methods for implant
planning using captured joint motion information.
[0004] 2. Description of Related Art
[0005] Orthopedic joint replacement surgery may involve
arthroplasty of a knee, hip, or other joint (e.g., shoulder, elbow,
wrist, ankle, fingers, etc.). For example, traditional total knee
arthroplasty involves a long incision, typically in a range of
about 6 to 12 inches, to expose the joint for bone preparation and
implantation of implant components. The invasive nature of the
incision results in a lengthy recovery time for the patient.
Minimally invasive surgery (MIS) reduces the incision length for a
total knee replacement surgery to a range of about 4 to 6 inches.
However, the smaller incision size reduces a surgeon's ability to
view and access the anatomy of a joint. Consequently, the
complexity of assessing proper implant position and reshaping bone
increases, and accurate placement of implants may be more
difficult. Inaccurate positioning of implants may lead to reduced
range of motion of a joint, impingement, and subsequent
dislocation. For example, one problem with total hip replacement is
dislocation of a femoral implant from an acetabular cup implant
caused, for example, by impingement, which in turn may be caused by
inaccurate positioning of the acetabular cup implant within a
pelvis.
[0006] Another drawback of both MIS and traditional orthopedic
surgical approaches is that such approaches do not enhance the
surgeon's inherent surgical skill in a cooperative manner. For
example, some conventional techniques for joint replacement include
autonomous robotic systems to aid the surgeon. Such systems,
however, typically serve primarily to enhance bone machining by
performing autonomous cutting with a high speed burr or by moving a
drill guide into place and holding the position of the drill guide
while the surgeon inserts cutting tools through the guide. Although
such systems enable precise bone resections for improved implant
fit and placement, they act autonomously (rather than cooperatively
with the surgeon) and thus require the surgeon to cede a degree of
control to the robot.
[0007] Other conventional robotic systems include robots that
cooperatively interact with the surgeon. One drawback of
conventional interactive robotic systems is that such systems lack
the ability to adapt surgical planning and navigation in real-time
to a dynamic intraoperative environment. For example, U.S. Pat. No.
7,035,716, which is hereby incorporated by reference herein in its
entirety, discloses an interactive robotic system programmed with a
three-dimensional virtual region of constraint that is registered
to a patient. The interactive robotic system requires a relevant
anatomy to be rigidly restrained and the robotic system to be fixed
in a gross position and thus lacks real-time adaptability to the
intraoperative scene. Moreover, a three degree of freedom arm
configuration and the requirement that the surgeon manipulate the
arm using a force handle results in limited flexibility and
dexterity, making the robotic system unsuitable for certain MIS
applications such as intraoperative implant planning.
[0008] An important aspect of implant planning concerns variations
in individual anatomies. As a result of anatomical variation, there
is no single implant design or orientation of implant components
that provides an optimal solution for all patients. Some
conventional intraoperative positioning devices for implant
planning used by surgeons to align an acetabular hip implant with
respect to the sagittal and coronal planes of a patient assume that
the patient's pelvis and trunk are aligned in a known orientation
and do not take into account individual variations in the patient's
anatomy or pelvic position on the operating room table. B. F.
Morrey, editor, "Reconstructive Surgery of the Joints", chapter
Joint Replacement Arthroplasty, pages 605-608, Churchill
Livingston, 1996. Implant planning based on such types of
conventional devices can lead to a large discrepancy between
desired and actual implant placement, possibly resulting in reduced
range of motion of a joint, impingement, and dislocation.
[0009] Several attempts have been made to more precisely prepare
the acetabular region for hip implants. U.S. Pat. Nos. 5,880,976;
5,995,738; 6,002,859; and 6,205,411, issued to DiGioia et al. and
hereby incorporated by reference herein in their entirety, are
directed to biomechanical simulations of the movement of a joint
containing implant models performed under a number of test
positions, including a desired range of motion of the joint.
Although the DiGioia patents describe a system that may offer the
potential for increased accuracy and consistency in the preparation
of the acetabular region to receive implants, a shortcoming of the
system is that movement of the joint is only simulated. The
accuracy and consistency of the actual implant results depend on
how closely the simulated motion of the joint corresponds to the
actual motion of the joint. Moreover, simulated joint movement does
not account for actual motion of a joint with individual
variations.
[0010] U.S. Pat. Nos. 5,086,401; 5,299,288; and 5,408,409, issued
to Glassman et al. and hereby incorporated by reference herein in
their entirety, disclose an image directed surgical robotic system
for broaching a femur to accept a femoral implant using a robotic
cutter system. In the system, the coordinates and structure of a
joint model are determined during an intraoperative planning phase
where a surgeon manually interactively selects and positions an
implant relative to images of the joint into which the implant is
to be implanted. Although the Glassman patents describe a system
that may offer the potential for increased accuracy and consistency
in the preparation of bones to receive implants, the system lacks
real-time adaptability to the intraoperative scene and consistent,
predictable results regardless of surgical skill level because the
surgeon manually has to interact and analyze relative discrete
positions of implants in a joint rather than analyzing the implants
during continuous motion of the joint.
[0011] In view of the foregoing, a need exists for surgical methods
and devices which can overcome the aforementioned problems so as to
enable intraoperative implant planning for accurate placement and
implantation of joint implants providing an improved range of
motion of a joint; consistent, predictable operative results
regardless of surgical skill level; sparing healthy bone in
minimally invasive surgery; and reducing the need for replacement
and revision surgery.
SUMMARY OF THE INVENTION
[0012] In one aspect, there is a surgical planning method. The
method includes capturing data representative of a range of motion
of a joint associated with a particular individual, the joint
comprising a first bone and a second bone, representing the first
bone of the joint, and associating a first implant model with the
representation of the first bone. The method also includes, based
on the captured data, determining a relationship between the first
implant model and a representation of the second bone through at
least a portion of the range of motion of the joint and displaying
information representative of the determined relationship.
[0013] In another aspect, there is a surgical planning method. The
method includes capturing data representative of a range of motion
of a joint associated with a particular individual, the joint
comprising a first bone and a second bone, creating a
representation of the joint comprising a representation of the
first bone and a representation of the second bone, and
superimposing a first implant model on the representation of the
first bone and a second implant model on the representation of the
second bone. The method also includes, based on the captured data,
displaying the representations of the first and second bones as the
representation of the joint moves through the range of motion to
determine a relationship between the first and second implant
models and adjusting a size, a shape, a position, or any
combination thereof of the first implant model, the second implant
model, or both based on the determined relationship.
[0014] In another aspect, there is a surgical computing system that
includes a computer. The computer is configured to capture data
representative of a range of motion of a joint associated with a
particular individual, represent a first bone of the joint, and
associate a first implant model with the representation of the
first bone. The computer is also configured to, based on the
captured data, determine a relationship between the first implant
model and a representation of a second bone of the joint through at
least a portion of the range of motion of the joint.
[0015] Any of the above aspects can include one or more of the
following features. A user can be enabled to change a position of
the first implant model. The first implant model can be associated
with the representation of the first bone based on the changed
position and, based on the captured data, a relationship between
the first implant model at its changed position and a
representation of the second bone can be determined through at
least a portion of the range of motion of the joint. The
representation of the second bone can include a representation of a
surface of the second bone, a second implant model associated with
the representation of the second bone, or both.
[0016] A position of the first bone and a position of the second
bone can be captured and the positions can be record as the joint
moves through the range of motion. The position of the first
implant model can be represented relative to a position of the
representation of the second bone and the positions at any selected
angle can be compared within the range of motion of the joint,
inclusive. A position of the first bone and a position of the
second bone can be captured and the positions can be record as the
joint moves through the range of motion. The position of the first
implant model can be represented relative to a position of the
representation of the second implant model and the positions at any
selected angle can be compared within the range of motion of the
joint, inclusive
[0017] An overlap, a gap, or both can be identified between the
first implant model and the representation of the second bone or
between the first implant model and a second implant model
associated with the second bone at one or more angles within the
range of motion of the joint, inclusive. A calculated measurement
of the overlap, the gap, or both at any selected angle or at a
plurality of angles within the range of motion of the joint,
inclusive, can be displayed. A graph representing calculated
measurements of the overlap, the gap, or both at a plurality of
angles within the range of motion of the joint, inclusive, can be
displayed. The overlap, the gap, or both can be displayed in a
representation of at least a portion of the joint at one or more
angles within the range of motion of the joint, inclusive.
[0018] At least one point on a surface of the first implant model
can be mapped at a plurality of angles within the range of motion
of the joint, inclusive and at least one of the mapped points can
be aligned with the representation of the second bone. A second
implant model can be associated with the representation of the
second bone based on at least one of the mapped points. Data
representative of a manipulation of the joint can be captured to
achieve a desired internal/external angle, varus/valgus angle,
flexion angle, or any combination thereof. A user can be enabled to
manipulate placement of at least one implant model corresponding to
at least a portion of an actual implant so that the determined
relationship through at least a portion of the range of motion of
the joint allows the desired internal/external angle, varus/valgus
angle, flexion angle, or any combination thereof.
[0019] The surgical computing system can include a tracking system
in communication with the computer, the tracking system including a
detection device and one or more trackers which each include a
coupling means to couple the tracker to a bone of the joint. The
surgical computing system can include a display in communication
with the computer and configured to display information received
from the computer that is representative of the determined
relationship. The computer of the surgical computing system can be
further configured to generate a user interface that enables a user
to select an angle at which the determined relationship is
calculated, displayed, or both. The computer of the surgical
computing system can be further configured to generate a user
interface that enables a user to change a position of the first
implant model.
[0020] There can also be a computer program product, tangibly
embodied in an information carrier, where the computer program
product includes instructions being operable to cause a data
processing apparatus to perform any of the methods described
above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
principles of the invention.
[0022] FIG. 1(a) is a front perspective view of a femur and a tibia
of a knee joint at a flexion angle of 0 degrees.
[0023] FIG. 1(b) is a perspective view of a conventional total knee
arthroplasty system.
[0024] FIG. 1(c) is a perspective view of a conventional bicondylar
knee arthroplasty system.
[0025] FIG. 2 illustrates a range of motion and a flexion angle of
a knee joint.
[0026] FIG. 3 is a front cross sectional view of an embodiment of a
representation of a joint at a flexion angle of 0 degrees.
[0027] FIG. 4 is a front perspective view of the representation of
FIG. 3.
[0028] FIG. 5 illustrates an embodiment of a computer display of a
gap analysis at a flexion angle of 0 degrees.
[0029] FIG. 6 is a side view of the femur and the tibia of FIG. 1
at a flexion angle of 90 degrees.
[0030] FIG. 7 is a front cross sectional view of an embodiment of a
representation of a joint at a flexion angle of 90 degrees.
[0031] FIG. 8 is a front perspective view of the representation of
FIG. 7.
[0032] FIG. 9 illustrates an embodiment of a computer display of an
overlap analysis at a flexion angle of 90 degrees.
[0033] FIG. 9(a) illustrates an embodiment of a computer display of
a graph of the gap/overlap analysis over a range flexion
angles.
[0034] FIG. 10 is a side view of an embodiment of a representation
of a joint at a first flexion angle.
[0035] FIG. 11 is a side view of the representation of FIG. 10 at a
second flexion angle and showing an embodiment of a point mapping
of a first implant model.
[0036] FIG. 12 is a side view of the representation of FIG. 10 at a
third flexion angle and showing an embodiment of a point mapping of
a first implant model.
[0037] FIG. 13 is a side view of the representation of FIG. 10
showing an embodiment of a point mapping of a first implant model
and a second implant model positioned relative to the point
mapping.
[0038] FIG. 14 illustrates an exemplary surgical computer system
for implant planning using captured joint motion information.
[0039] FIG. 15 illustrates an exemplary tracker used by the
surgical computer system for implant planning using captured joint
motion information.
[0040] FIG. 16 illustrates an exemplary method for implant planning
using captured joint motion information.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0041] Presently preferred embodiments are illustrated in the
drawings. Although this specification refers primarily to
unicondylar knee joint replacement surgery, it should be understood
that the subject matter described herein is applicable to other
joints in the body, such as, for example, a shoulder, elbow, wrist,
spine, hip, or ankle and to any other orthopedic and/or
musculoskeletal implant, including implants of conventional
materials and more exotic implants, such as orthobiologics, drug
delivery implants, and cell delivery implants.
Representation of a Joint and Implant Models
[0042] FIG. 1(a) shows a front view of a tibia T (e.g., a first
bone) and a femur F (e.g., a second bone) of a joint 120 without
any implant and with the joint 120 at full extension (i.e., a
flexion angle .theta. of 0 degrees). Position trackers (e.g., such
as those shown in FIG. 15 and described in more detail below) that
are detectable by a detection device, such as an optical camera,
are affixed to the femur F and the tibia T of the joint 120. The
detected position of the tibia tracker relative to the femur
tracker is captured or recorded in given degree intervals (e.g., 3
degrees) as the joint 120 is moved throughout the normal range of
motion of the joint 120 from extension to flexion, or any desired
set of anatomical orientation angles (for the knee, flexion or
extension, varus or valgus, internal or external rotations). The
captured movement of the femur F and the tibia T of the joint 120
is registered, respectively, to images of the femur F and the tibia
T (e.g., to segmented CT data of the femur F and the tibia T
acquired before the surgery begins and/or to representations or
models of the femur F and the tibia T generated, for example, from
the segmented CT data). This registration establishes coordinate
transformations between the position trackers on the femur F and
the tibia T (i.e., the physical space) and the respective images of
the femur F and the tibia T (i.e., the image space) so that the
position of the physical bones can be correlated to the images of
the bones. Segmentation and registration may be accomplished using
any known technique, such as the techniques described in U.S.
Patent Publication 2006/0142657, published Jun. 29, 2006, which is
hereby incorporated by reference herein in its entirety. Similarly,
coordinate transformations may be determined using any known
technique, such as the techniques described in U.S. patent
application Ser. No. 11/750,840, filed May 18, 2007, which is
hereby incorporated by reference herein in its entirety.
[0043] FIG. 1(b) shows, and exemplary conventional total knee
arthroplasty (TKA) systems typically include, a femoral implant 100
and a tibial implant 102. The femoral implant 100 is typically a
single solid component affixed to the femur F. The tibial implant
102 may include a tibial baseplate 102a affixed to the tibia T and
a tibial insert 102b which forms the bearing surfaces 104 of the
tibial implant 102. In operation, bearing surfaces 103 of the
femoral implant 100 articulate against the bearing surfaces 104 of
the tibial implant 102 as the knee joint 120 moves through a range
of motion.
[0044] FIG. 1(c) shows a perspective view of the tibia T and the
femur F of the knee joint 120 with multiple unconnected implants
105. The unconnected implants 105 may form a bicondylar implant (as
shown in FIG. 1(c)), a unicondylar implant, or a modular segmented
implant as described, for example, in U.S. patent application Ser.
No. 11/684,514, filed Mar. 9, 2007, and hereby incorporated by
reference herein in its entirety. These unconnected implants 105
may require accurate alignment relative to one another to achieve
desired joint kinematics and/or to avoid reduced range of joint
motion, impingement, and subsequent dislocation. To achieve these
objectives, the surgeon can virtually plan implant placement prior
to making any bone cuts. Implant planning may be accomplished, for
example, as described in the above-referenced U.S. Patent
Publication 2006/0142657. According to some embodiments, the femur
F and the tibia T of the knee joint 120 with the implants 105 may
be virtually represented and their relative positions manipulated
and analyzed by performing matrix transformations using the
segmented CT data as described below.
[0045] Let T.sub.tf be the transform from the tibia tracker to the
femur tracker at any desired flexion angle. Let T.sub.td and
T.sub.fd be the transforms from the tibia tracker to the tibia CT
data and from the femur tracker to the femur CT data, respectively.
Then the segmented CT data of the tibia T can be positioned
relative to the segmented CT data of the femur F using the matrix
composition T.sub.td.sup.-1 T.sub.tf T.sub.fd, where the
superscript "-1" denotes matrix inversion. Similarly, the segmented
CT data of the femur F can be positioned relative to the segmented
CT data of the tibia T using the matrix composition T.sub.fd.sup.-1
T.sub.tf.sup.-1 T.sub.td.
[0046] FIG. 3 shows a cross sectional view of a 2D display of a
virtual representation 12 of the joint 120 at a flexion angle
.theta. of 0 degrees. Similarly, FIG. 4 shows a 3D display of the
virtual representation 12 of the joint 120 at a flexion angle
.theta. of 0 degrees. As shown in FIG. 3, the virtual
representation 12 of the joint 120 can include a representation 10
of the femur F and a representation 11 of the tibia T. A tibial
implant model 30 (e.g., a first implant model) and a femoral
implant model 20 (e.g., a second implant model) can be associated
with (i.e., registered to) the representation 11 of the tibia T and
the representation 10 of the femur F, respectively. This may be
accomplished in any known manner, such as, for example, the implant
planning process described in the above-referenced U.S. Patent
Publication 2006/0142657. In some embodiments, the representations
10, 11 are graphic models of the femur F and the tibia T generated
from the segmented CT data as is well known. To directly compare
two implant models at any desired flexion angle let T.sub.ifd be
the transform from the femoral implant model 20 to the femoral CT
data and T.sub.itd be the transform from the tibial implant model
30 to the tibial CT data. Then the femoral implant model 20 can be
positioned relative to the tibial implant model 30 at any desired
flexion angle .theta. by using the relationship T.sub.ifd
T.sub.fd.sup.-1 T.sub.tf.sup.-1 T.sub.td T.sub.itd.sup.-1.
[0047] This registration enables the captured data representing the
range of motion of the joint 120 to be "played back" to the user so
that the user can visualize the relative motion of the
"disarticulated" segmented femur F and tibia T of the CT data with
the femoral and tibial implant models 20, 30 superimposed on the
representations 10, 11 of the femur F and the tibia T of the joint
120. For example, the actual physical motion of the joint 120 can
be visualized by displaying the representation 10 of the femur F
and the representation 11 of the tibia T and moving the
representations 10, 11 in accordance with how the femur F and the
tibia T actually move (i.e., based on the captured range of motion
data). When the implant models 20, 30 are superimposed on the
representations 10, 11 (e.g., as shown in FIG. 3), the relative
position of the implant models 20, 30 can be seen at any selected
angle within the range of motion of the joint 120. The user can
also determine whether there is a gap (i.e., a space) or an overlap
(i.e., an interference) between the implant models 20, 30 at any
selected angle within the range of motion of the joint 120. Gap and
overlap are discussed further below in connection with FIGS. 5 and
9.
[0048] Anatomical axes can be defined in the CT data for the femur
F and tibia T of the joint 120. Once this has been done, anatomical
angles (e.g., flexion angle, varus/valgus angle, internal/external
angle) for any position of the joint 120 can be computed and
displayed for any orientation of the captured data representing the
range of motion or in "real time" as the joint 120 is manipulated.
FIG. 6 shows a side view of the femur F and the tibia T of the
joint 120 without any implant at a flexion angle .theta. of 90
degrees. The amount of gap or overlap between the implant models
20, 30 can be determined for the implant models 20, 30 associated
with (e.g., superimposed on) the representations 10, 11 of the
femur F and the tibia T at a selected flexion angle .theta. (e.g.,
0 degrees as shown in FIG. 3, 90 degrees as shown in FIG. 6) of the
joint 120. This information can be used to plan the placement in
the joint 120 of the actual implants that correspond to the implant
models 20, 30. For an example, if an overlap 70 is detected between
the implant models 20, 30 (as shown in FIGS. 7 and 8), the surgeon
may decide to reposition the femoral implant model 20 and/or the
tibial implant model 30 to eliminate the overlap 70.
[0049] According to some embodiments, one or more implant models
may be used. For example, as described above, in one embodiment,
both the femoral implant model 20 and the tibial implant model 30
may be used to evaluate relative positions of the two implant
models 20, 30. This embodiment may be useful in cases where a
patient is having both the femur F and the tibia T resurfaced. In
such cases, the implant models 20, 30 can be used to plan placement
of the actual femoral and tibial implant components that will be
implanted in the femur F and the tibia T of the patient.
Alternatively, in another embodiment, only the tibial implant model
30 may be used to evaluate relative positions between the tibial
implant model 30 and a surface of the representation 10 of the
femur F. The surface of the representation 10 may correspond, for
example, to an actual surface of the patient's femur F or to
previously installed implant that is now part of the patient's
joint 120. This embodiment may be useful in cases where the femur F
is not being resurfaced at all or where a previously installed
femoral implant is not being replaced or modified. Similarly, in
another embodiment, only the femoral implant model 20 may be used
to evaluate relative positions of the femoral implant model 20 and
a surface of the representation 11 of the tibia T. The surface of
the representation 11 may correspond, for example, to an actual
surface of the patient's tibia T or to a previously installed
implant that is now part of the patient's joint 120. In other
embodiments, additional implant models may be included, such as
models of the modular segmented components described in U.S. patent
application Ser. No. 11/684,514, filed Mar. 9, 2007, and hereby
incorporated by reference herein in its entirety.
Overlap and Gap Analysis
[0050] As described above, the placement of one implant model
relative to another or the placement of an implant model relative
to a surface of a bone can be visualized and analyzed throughout
the range of motion of the joint 120. For example, the relative
placement of the tibial implant model 30 and the femoral implant
model 20 can be visualized and evaluated. In one embodiment, when
the lowest signed distance between the surface of the femoral
implant model 20 and the surface of the tibial implant model 30 is
a positive value, a gap 31 is detected between the implant models
20, 30 as shown in FIGS. 3 and 4.
[0051] FIG. 5 shows an example computer display of a gap analysis
of the positions of the implant models 20, 30. In one embodiment,
the computer display includes a user input 50 for inputting a
selected flexion angle .theta. and an indicator 51 that shows a
value of the gap 31 at the selected flexion angle .theta.. In the
example of FIG. 5, at a flexion angle of 0 degrees, there is a gap
31 of 1.2 mm between the femoral implant model 20 and the tibial
implant model 30. Likewise, when the lowest signed distance between
the surfaces of the implant models 20, 30 is a negative value, an
overlap is detected between the implant models 20, 30.
[0052] FIG. 7 shows a front cross sectional view of a 2D display of
the representations 10, 11 of the femur F and tibia T. Also shown
in FIG. 7 are the implant models 20, 30 associated with the
representations 10, 11 of the femur F and the tibia T at a flexion
angle .theta. of 90 degrees.
[0053] FIG. 8 shows a front view of a 3D display of the
representations 10, 11 of the femur F and the tibia T associated
with the representations of the femoral implant model 20 and the
tibial implant model 30 at a flexion angle .theta. of 90
degrees.
[0054] FIG. 9 shows an example of a computer display of an overlap
analysis of the positions of the implant models 20, 30 at a flexion
angle .theta. of 90 degrees. In one embodiment, the computer
display includes a user input 90 for inputting a selected flexion
angle .theta. and an indicator 91 that shows that the value of the
overlap 70 at the selected flexion angle .theta.. In the example of
FIG. 9, at a flexion angle of 90 degrees, there is an overlap of
0.3 mm between the femoral implant model 20 and the tibial implant
model 30. Based on the information provided by the virtual analysis
shown in FIGS. 5 and 9, when a surgeon is planning the placement of
actual implants corresponding to the implant models 20, 30, he can
adjust the implant models 20, 30 to achieve the desired
relationship between the implant models 20, 30 at any selected
angle within the range of motion of the joint. For example, the
surgeon may adjust the implant models 20, 30 to ensure that the gap
31 is filled at the flexion angle of 0 degrees and the overlap 70
is removed at the flexion angle of 90 degrees by repositioning the
implant models 20, 30 until the surfaces of the implant models 20,
30 just "touch" each other at selected angles within the range of
motion of the joint 120.
[0055] FIG. 9(a) shows another example of a computer display with a
graph 600 that graphs the gap/overlap analysis of the positions of
the implant models 20, 30 over a range of flexion angles. The
horizontal axis of the graph 600 displays the value of the flexion
angle. Although the exemplary graph 600 includes angles 12.5
degrees through 108.5 degrees, any range of angles can be
displayed. The vertical axis of the graph 600 displays the value of
the calculated gap or overlap between two measured points (e.g.,
the first implant and the second bone, the first implant and the
second implant, etc.). In the graph 600, the positive axis
represents a gap between the two measured points, with the number
representing the distance of the gap, in millimeters. In the graph
600, the negative axis represents an overlap between the two
measured points, with the number representing the distance of the
overlap, in millimeters. As described herein, the position of the
implant(s) can be manipulated through the user interface, so that
the surgeon can see the gap/overlap analysis at different implant
positions. In such situations, the graph 600 updates as the implant
positions are adjusted. With the graph, the user (e.g., the
surgeon) can advantageously see all gaps and overlaps over the
entire range in one display. This enables the user to slightly
modify the position of the implant(s) and receive feedback on the
modification over the entire range. The user can then adjust the
position to achieve a desired goal (e.g., minimize all gaps and
overlaps, minimize center gaps and overlaps at the expense of
larger gaps and overlaps at the ends of the range, etc.).
[0056] The movement of the femur F and tibia T of the joint 120 can
be captured and registered both before and after bone cutting and
can be used to compare preoperative and intraoperative ranges of
motion of the joint 120 to determine if any over-correction or
under-correction has occurred. Accordingly, the surgeon can adjust
the plan and continue to cut the bone to adjust for any
problems.
Mapped Points Analysis
[0057] Referring to FIGS. 11-13, further analysis can be performed
by selecting one or more points on the articulating surface of a
first implant model (e.g., points near the center, anterior, and
posterior of the surface of the tibial implant model 30), mapping
these points at multiple angles of joint flexion into the space of
an opposite bone (e.g., the representation 10 of the femur F)
and/or a second counterpart implant model (e.g., the femoral
implant model 20) using the transform relationships described
previously, and displaying these mapped points in 3D or projected
2D relative to the opposite bone and/or the second implant model.
Mapping may be accomplished, for example, by determining a position
of each of the selected points at each of the multiple angles of
joint flexion. These "mapped" points can then be used to guide the
placement of the second implant model. For example, the second
implant model (e.g., the femoral implant model 20) can be
positioned so that the articulating surface of the second implant
model has a desired relationship to the articulating surface of the
first implant model (e.g., the tibial implant model 30) as
represented by the mapped points. Similarly, the first implant
model (e.g., the tibial implant model 30) can be positioned so that
the articulating surface of the first implant model will have a
desired relationship to the articulating surface of the opposite
bone (e.g., the representation 10 of the femur F). Repositioning
the first implant model will update the positions of the mapped
points so that the relationship of the second implant model and/or
the opposite bone to the first implant model can always be
reestablished.
[0058] One example of this is to select central, anterior, and
posterior points on the surface of a tibial implant model and use
these mapped points to align the position and orientation of a
femoral implant model as illustrated in FIGS. 11-13.
[0059] For example, FIG. 10 shows a side view of a representation
12 of the joint 120. The representation 12 includes the
representations 10, 11 of the femur F and the tibia T,
respectively, for the joint 120 at a flexion angle of 0 degrees. A
first implant model 30 is associated with (e.g., superimposed on or
registered to) the representation 11 of the tibia T. The
representations 10, 11 can be used to accomplish point mapping.
According to some embodiments, as shown in FIGS. 11 and 12, one or
more points 110 of an articulating surface 111 of the first implant
model 30 can be mapped to an articular space 112 of the femur F at
multiple angles of the range of motion of the joint 120. The mapped
points 113 are preferably displayed relative to the representations
10, 11. FIG. 11 shows the mapped points 113 with the representation
12 of the joint 120 at a flexion angle of approximately 30 degrees.
FIG. 12 shows the mapped points 113 with the representation 12 of
the joint 120 at a flexion angle of approximately 135 degrees.
[0060] FIG. 13 shows the representations 10, 11 of FIG. 11, the
first implant model 30 that has been associated with the
representation 11, and a second implant model 20 that has been
associated with the representation 10. In some embodiments, the
second implant model 20 may be associated with the representation
10 by aligning the articular surface of the second implant model 20
with at least one of the mapped points 113 as shown in FIG. 13. In
this manner, a desired relationship between the implant models 20,
30 may be achieved. As a result, the physical implant components
(which correspond to the implant models 20, 30) will have the
desired relative placement through some or all of the range of
motion of the joint 120 when implanted in the patient's joint 120
by the surgeon.
[0061] FIG. 14 shows an embodiment of an exemplary surgical
computer system 210 in which the techniques described above can be
implemented. Such an exemplary system is described in detail, for
example, in U.S. Patent Publication 2006/0142657, published Jun.
29, 2006, which is hereby incorporated by reference herein in its
entirety. The surgical system 210 includes a computing system 220,
a haptic device 230, and a tracking (or localizing) system 240. In
operation, the surgical system 210 enables comprehensive,
intraoperative surgical planning. The surgical system 210 also
provides haptic guidance to a user (e.g., a surgeon) and/or limits
the user's manipulation of the haptic device 230 as the user
performs a surgical procedure. Although included for completeness
in the illustrated embodiment, the haptic device 230 and its
associated hardware and software is not necessary to perform the
techniques described herein.
[0062] The computing system 220 includes hardware and software for
operation and control of the surgical system 210. Such hardware
and/or software is configured to enable the system 210 to perform
the techniques described herein. In FIG. 14, the computing system
220 includes a computer 221, a display device 223, and an input
device 225. The computing system 220 may also include a cart
229.
[0063] The computer 221 may be any known computing system but is
preferably a programmable, processor-based system. For example, the
computer 221 may include a microprocessor, a hard drive, random
access memory (RAM), read only memory (ROM), input/output (I/O)
circuitry, and any other well-known computer component. The
computer 221 is preferably adapted for use with various types of
storage devices (persistent and removable), such as, for example, a
portable drive, magnetic storage (e.g., a floppy disk), solid state
storage (e.g., a flash memory card), optical storage (e.g., a
compact disc or CD), and/or network/Internet storage. The computer
221 may comprise one or more computers, including, for example, a
personal computer (e.g., an IBM-PC compatible computer) or a
workstation (e.g., a SUN or Silicon Graphics workstation) operating
under a Windows, MS-DOS, UNIX, or other suitable operating system
and preferably includes a graphical user interface (GUI).
[0064] The display device 223 is a visual interface between the
computing system 220 and the user. The display device 223 is
connected to the computer 221 and may be any device suitable for
displaying text, images, graphics, and/or other visual output. For
example, the display device 223 may include a standard display
screen (e.g., LCD, CRT, plasma, etc.), a touch screen, a wearable
display (e.g., eyewear such as glasses or goggles), a projection
display, a head-mounted display, a holographic display, and/or any
other visual output device. The display device 223 may be disposed
on or near the computer 221 (e.g., on the cart 229 as shown in FIG.
14) or may be remote from the computer 221 (e.g., mounted on a wall
of an operating room or other location suitable for viewing by the
user). The display device 223 is preferably adjustable so that the
user can position/reposition the display device 223 as needed
during a surgical procedure. For example, the display device 223
may be disposed on an adjustable arm (not shown) that is connected
to the cart 229 or to any other location well-suited for ease of
viewing by the user. The display device 223 may be used to display
any information useful for a medical procedure, such as, for
example, images of anatomy generated from an image data set
obtained using conventional imaging techniques, graphical models
(e.g., CAD models of implants, instruments, anatomy, etc.),
graphical representations of a tracked object (e.g., anatomy,
tools, implants, etc.), digital or video images, registration
information, calibration information, patient data, user data,
measurement data, software menus, selection buttons, status
information, and the like.
[0065] In addition to the display device 223, the computing system
220 may include an acoustic device (not shown) for providing
audible feedback to the user. The acoustic device is connected to
the computer 221 and may be any known device for producing sound.
For example, the acoustic device may comprise speakers and a sound
card, a motherboard with integrated audio support, and/or an
external sound controller. In operation, the acoustic device may be
adapted to convey information to the user. For example, the
computer 221 may be programmed to signal the acoustic device to
produce a sound, such as a voice synthesized verbal indication
"DONE," to indicate that a step of a surgical procedure is
complete. Similarly, the acoustic device may be used to alert the
user to a sensitive condition, such as producing a beep to indicate
that a surgical cutting tool is nearing a critical portion of soft
tissue.
[0066] The input device 225 of the computing system 220 enables the
user to communicate with the surgical system 210. The input device
225 is connected to the computer 221 and may include any device
enabling a user to provide input to a computer. For example, the
input device 225 can be a known input device, such as a keyboard, a
mouse, a trackball, a touch screen, a touch pad, voice recognition
hardware, dials, switches, buttons, a trackable probe, a foot
pedal, a remote control device, a scanner, a camera, a microphone,
and/or a joystick.
[0067] The computing system 220 is coupled to the computing device
231 via an interface 2100a and to a detection device 241 via an
interface 2100b. The interfaces 2100a and 2100b can include a
physical interface and a software interface. The physical interface
may be any known interface such as, for example, a wired interface
(e.g., serial, USB, Ethernet, CAN bus, and/or other cable
communication interface) and/or a wireless interface (e.g.,
wireless Ethernet, wireless serial, infrared, and/or other wireless
communication system). The software interface may be resident on
the computer 221 and/or the computer 231. In some embodiments,
computer 221 and 231 are the same computing device.
[0068] The system 210 also includes a tracking (or localizing)
system 240 that is configured to determine a pose (i.e., position
and orientation) of one or more objects during a surgical procedure
to detect movement of the object(s). For example, the tracking
system 240 may include a detection device that obtains a pose of an
object with respect to a coordinate frame of reference of the
detection device. As the object moves in the coordinate frame of
reference, the detection device tracks the pose of the object to
detect (or enable the surgical system 210 to determine) movement of
the object. As a result, the computing system 220 can capture data
in response to movement of the tracked object or objects. Tracked
objects may include, for example, tools/instruments, patient
anatomy, implants/prosthetic devices, and components of the
surgical system 210. Using pose data from the tracking system 240,
the surgical system 210 is also able to register (or map or
associate) coordinates in one space to those in another to achieve
spatial alignment or correspondence (e.g., using a coordinate
transformation process as is well known). Objects in physical space
may be registered to any suitable coordinate system, such as a
coordinate system being used by a process running on the computer
221 and/or the computer 231. For example, utilizing pose data from
the tracking system 240, the surgical system 210 is able to
associate the physical anatomy with a representation of the anatomy
(such as an image displayed on the display device 223). Based on
tracked object and registration data, the surgical system 210 may
determine, for example, a spatial relationship between the image of
the anatomy and the relevant anatomy.
[0069] Registration may include any known registration technique,
such as, for example, image-to-image registration (e.g., monomodal
registration where images of the same type or modality, such as
fluoroscopic images or MR images, are registered and/or multimodal
registration where images of different types or modalities, such as
MRI and CT, are registered); image-to-physical space registration
(e.g., image-to-patient registration where a digital data set of a
patient's anatomy obtained by conventional imaging techniques is
registered with the patient's actual anatomy); and/or combined
image-to-image and image-to-physical-space registration (e.g.,
registration of preoperative CT and MRI images to an intraoperative
scene). The computer system 210 may also include a coordinate
transform process for mapping (or transforming) coordinates in one
space to those in another to achieve spatial alignment or
correspondence. For example, the surgical system 210 may use the
coordinate transform process to map positions of tracked objects
(e.g., patient anatomy, etc.) into a coordinate system used by a
process running on the computer 231 and/or the computer 221. As is
well known, the coordinate transform process may include any
suitable transformation technique, such as, for example, rigid-body
transformation, non-rigid transformation, affine transformation,
and the like.
[0070] The tracking system 240 may be any tracking system that
enables the surgical system 210 to continually determine (or track)
a pose of the relevant anatomy of the patient. For example, the
tracking system 240 may comprise a non-mechanical tracking system,
a mechanical tracking system, or any combination of non-mechanical
and mechanical tracking systems suitable for use in a surgical
environment. The non-mechanical tracking system may include an
optical (or visual), magnetic, radio, or acoustic tracking system.
Such systems typically include a detection device adapted to locate
in predefined coordinate space specially recognizable trackable
elements (or trackers) that are detectable by the detection device
and that are either configured to be attached to the object to be
tracked or are an inherent part of the object to be tracked. For
example, a trackable element may include an array of markers having
a unique geometric arrangement and a known geometric relationship
to the tracked object when the trackable element is attached to the
tracked object. The known geometric relationship may be, for
example, a predefined geometric relationship between the trackable
element and an endpoint and axis of the tracked object. Thus, the
detection device can recognize a particular tracked object, at
least in part, from the geometry of the markers (if unique), an
orientation of the axis, and a location of the endpoint within a
frame of reference deduced from positions of the markers. The
markers may include any known marker, such as, for example,
extrinsic markers (or fiducials) and/or intrinsic features of the
tracked object. Extrinsic markers are artificial objects that are
attached to the patient (e.g., markers affixed to skin, markers
implanted in bone, stereotactic frames, etc.) and are designed to
be visible to and accurately detectable by the detection device.
Intrinsic features are salient and accurately locatable portions of
the tracked object that are sufficiently defined and identifiable
to function as recognizable markers (e.g., landmarks, outlines of
anatomical structure, shapes, colors, or any other sufficiently
recognizable visual indicator). The markers may be located using
any suitable detection method, such as, for example, optical,
electromagnetic, radio, or acoustic methods as are well known. For
example, an optical tracking system having a stationary stereo
camera pair sensitive to infrared radiation may be used to track
markers that emit infrared radiation either actively (such as a
light emitting diode or LED) or passively (such as a spherical
marker with a surface that reflects infrared radiation). Similarly,
a magnetic tracking system may include a stationary field generator
that emits a spatially varying magnetic field sensed by small coils
integrated into the tracked object.
[0071] In one embodiment, as shown in FIG. 14, the tracking system
240 includes a non-mechanical tracking system. In this embodiment,
the non-mechanical tracking system is an optical tracking system
that comprises a detection device 241 and at least one trackable
element (or tracker) configured to be disposed on (or incorporated
into) a tracked object and detected by the detection device 241. In
FIG. 14, the detection device 41 includes, for example, a stereo
camera pair sensitive to infrared radiation and positionable in an
operating room where the surgical procedure will be performed. The
tracker is configured to be affixed to the tracked object in a
secure and stable manner and includes an array of markers (e.g., an
array S1 in FIG. 15) having a known geometric relationship to the
tracked object. The markers may be active (e.g., light emitting
diodes or LEDs) or passive (e.g., reflective spheres, a
checkerboard pattern, etc.) and preferably have a unique geometry
(e.g., a unique geometric arrangement of the markers) or, in the
case of active, wired markers, a unique firing pattern. In
operation, the detection device 241 detects positions of the
markers, and the unique geometry (or firing pattern) and known
geometric relationship to the tracked object enable the surgical
system 210 to calculate a pose of the tracked object based on the
positions of the markers.
[0072] The non-mechanical tracking system may include a trackable
element (or tracker) for each object the user desires to track. For
example, in one embodiment, the non-mechanical tracking system
includes anatomy trackers 243a and 243b, generally 243 (to track
patient anatomy).
[0073] In FIG. 14, the anatomy tracker 243 is disposed on a
relevant portion of a patient's anatomy (such as a bone) and is
adapted to enable the relevant anatomy to be tracked by the
detection device 241. The anatomy tracker 243 includes a fixation
device for attachment to the anatomy. The fixation device may be,
for example, a bone pin, surgical staple, screw, clamp, wearable
device, intramedullary rod, or the like. In one embodiment, the
anatomy tracker 243 is configured for use during knee replacement
surgery to track a femur F and a tibia T of a patient. In this
embodiment, as shown in FIG. 14, the anatomy tracker 243 includes a
first tracker 243a adapted to be disposed on the femur F and a
second tracker 243b adapted to be disposed on the tibia T. FIG. 15
illustrates the first tracker 243a, which includes a fixation
device comprising bone pins P and a unique array S1 of markers
(e.g., reflective spheres). The array S1 is affixed to a connection
mechanism 400 that is adapted to be removably secured to both of
the bone pins P. For example, as shown in FIG. 15, the connection
mechanism 400 may include a first portion 442, a second portion
444, and screws 445. To install the first tracker 43a on the femur
F, the user screws the bone pins P into the femur F, slides the
connection mechanism 400 over the bone pins P, and tightens the
screws 445 to draw the first and second portions 442 and 444
together to thereby securely fix the connection mechanism 400 to
the bone pins P. Once secured, the connection mechanism 400 imparts
additional stability to the bone pins P. The second tracker 243b is
identical to the first tracker 243a except the second tracker 243b
is installed on the tibia T and has its own unique array of
markers. When installed on the patient, the first and second
trackers 243a and 243b enable the detection device 241 to track
motion of the femur F and the tibia T during knee replacement
surgery. As a result, the surgical system 210 is able to detect and
capture bone motion in real-time as an individual moves his or her
joint through its range of motion.
[0074] FIG. 16 illustrates an exemplary process 500 for implant
planning using captured joint motion information. In describing the
process 500, the exemplary system 210 of FIG. 14 will be used. In
FIG. 14, trackers 243a and 243b are inserted into the femur F and
tibia T, respectively. After these trackers are securely attached
to the bones of the knee joint, the trackers are registered (505)
using tracking system 240 and computing system 220. Once
registered, the computing system 220 captures (510) pose data of
the femur relative to tibia at a particular angle, for example zero
degrees (e.g., full extension). Capturing data refers to storing
the data, at least on a temporary basis. Capturing can also refer
to the detection of the pose data, for example, through the use of
trackers and a detection device, and the transmission of that data
to its storage location or some processing device that uses the
data. Although pose data (position and orientation) is captured in
the process 500, it is not necessary to use pose data in all
embodiments. For example, some embodiments, including embodiments
using system 210, can use less than all of the pose data, for
example only position data, to implement the techniques described
herein.
[0075] In the process 500, for example using the transform process
as described above, the computing system 220 associates (515) the
pose data with the one or more stored representations of the bones
of the joint. These representations can include images and/or
models of the bones, such as segmented CT data, that have been
generated for the particular individual for which the bone pose
data is being captured (510).
[0076] The computing system 220 determines (520) whether any more
data is needed for the range of motion. This can be automated, for
example by having a set of predetermined angles at which data is
collected. If data has not been taken at each of the predetermined
angles, the computing system 220 determines (520) that additional
data is needed and displays or otherwise communicates to the
operator the next angle to which the joint should be positioned.
Upon indication by the operator that the joint is at the indicated
position, the computing system 220 communicates with the tracking
system 240 to retrieve the pose of the trackers and repeats steps
510 and 515. In addition or as an alternative to the set of
predetermined angles, the computing system 220 can, through an
interface (e.g., displayed text, voice synthesis, etc.), ask the
operator whether there are any additional angles at which data
should be taken. Typically, there are at least two angles at which
data is captured to calculate the relative positions of the bones
through a range of motion of the joint.
[0077] If there are no more angles at which data needs to be
captured, the computing system 220 can calculate (525) the position
of the implant model in the joint representation. Such a
calculation can take into account input from the user. More
specifically, the user of system 220 can, for example through the
use of a GUI, manipulate the placement of the implant within the
joint representation. Using the implant position and the captured
pose data, or some derivative thereof, the computing system 220 can
determine (530) the relationship (e.g., a physical distance)
between the implant boundaries and the boundaries of a bone of the
joint with which the implant will interact. The computer system 220
displays (535) the determined relationship. As described above,
there are many ways in which the determined relationship can be
displayed, such as a measurement, a graph of the measurement at
some or all joint angles, a visual representation of the implant
and joint, and mapped points.
[0078] The above-described techniques can be implemented in digital
electronic circuitry, or in computer hardware, firmware, software,
or in combinations of them. The implementation can be as a computer
program product, i.e., a computer program tangibly embodied in an
information carrier, e.g., in a machine-readable storage device,
for execution by, or to control the operation of, data processing
apparatus, e.g., a programmable processor, a computer, or multiple
computers. Information carriers suitable for embodying computer
program instructions and data include all forms of non-volatile
memory, including by way of example semiconductor memory devices,
e.g., EPROM, EEPROM, and flash memory devices; magnetic disks,
e.g., internal hard disks or removable disks; magneto-optical
disks; and CD-ROM and DVD-ROM disks. A computer program can be
written in any form of programming language, including compiled or
interpreted languages, and it can be deployed in any form,
including as a stand-alone program or as a module, component,
subroutine, or other unit suitable for use in a computing
environment. A computer program can be deployed to be executed on
one computer or on multiple computers at one site or distributed
across multiple sites and interconnected by a communication
network.
[0079] Method steps can be performed by one or more programmable
processors executing a computer program to perform functions of the
invention by operating on input data and generating output. Method
steps can also be performed by, and apparatus can be implemented
as, special purpose logic circuitry, e.g., an FPGA (field
programmable gate array) or an ASIC (application-specific
integrated circuit). Modules can refer to portions of the computer
program and/or the processor/special circuitry that implements that
functionality.
[0080] The above described techniques can be implemented in a
distributed computing system that includes a back-end component,
e.g., as a data server, and/or a middleware component, e.g., an
application server, and/or a front-end component, e.g., a client
computer having a graphical user interface and/or a Web browser
through which a user can interact with an example implementation,
or any combination of such back-end, middleware, or front-end
components. The components of the system can be interconnected by
any form or medium of digital data communication, e.g., a
communication network. Examples of communication networks include a
local area network ("LAN") and a wide area network ("WAN"), e.g.,
the Internet, and include both wired and wireless networks.
[0081] The computing system can include clients and servers. A
client and server are generally remote from each other and
typically interact through a communication network. The
relationship of client and server arises by virtue of computer
programs running on the respective computers and having a
client-server relationship to each other.
[0082] Comprise, include, have and/or plural forms of each are open
ended and include the listed parts and can include additional parts
that are not listed. And/or is also open ended and includes one or
more of the listed parts and combinations of the listed parts.
[0083] The invention has been described in terms of particular
embodiments. The alternatives described herein are examples for
illustration only and not to limit the alternatives in any way. The
steps of the invention can be performed in a different order and
still achieve desirable results. Other embodiments are within the
scope of the following claims.
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